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<h1>isobel</h1><p><span class="helptopic">Sobel edge detector</span></p><strong>out</strong> = <span style="color:red>isobel</span>(<strong>im</strong>) is an edge image computed using the Sobel edge operator
applied to the image <strong>im</strong>.  This is the norm of the vertical and horizontal
gradients at each pixel.  The Sobel kernel is:

<pre style="width: 90%%;" class="examples">
|&nbsp;-1&nbsp;&nbsp;0&nbsp;&nbsp;1|
|&nbsp;-2&nbsp;&nbsp;0&nbsp;&nbsp;2|
|&nbsp;-1&nbsp;&nbsp;0&nbsp;&nbsp;1|
</pre>
<strong>out</strong> = <span style="color:red>isobel</span>(<strong>im</strong>,<strong>dx</strong>) as above but applies the kernel <strong>dx</strong> and <strong>dx</strong>' to compute
the horizontal and vertical gradients respectively.

[<strong>gx</strong>,<strong>gy</strong>] = <span style="color:red>isobel</span>(<strong>im</strong>) as above but returns the gradient images.

[<strong>gx</strong>,<strong>gy</strong>] = <span style="color:red>isobel</span>(<strong>im</strong>,<strong>dx</strong>) as above but returns the gradient images.

<h2>Notes</h2>
<ul>
  <li>Tends to produce quite thick edges.</li>
  <li>The resulting image is the same size as the input image.</li>
</ul>
<h2>See also</h2>
<p>
<a href="matlab:doc ksobel">ksobel</a>, <a href="matlab:doc icanny">icanny</a>, <a href="matlab:doc iconv">iconv</a></p>
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